Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 5: Plasmonics: Nanoantennas, Nanoparticles
O 5.9: Talk
Monday, March 16, 2015, 12:30–12:45, MA 042
Near-field trapping of nanoparticles on plasmonic nanoantenna arrays — •Anastasia Babynina1,2,3 and Theobald Lohmüller1,2,3 — 1Photonics and Optoelectronics Group, Ludwig Maximilian University of Munich, Munich, Germany — 2Nanosystems Initiative Munich (NIM), Munich, Germany — 3The Center for NanoScience (CeNS), Munich, Germany
Optical trapping of nano-sized particles is challenging. In general, high laser powers are required to generate sufficient gradient forces for keeping such small objects confined in a trap. This is particularly problematic for biological samples. Plasmonically coupled nanostructures, such as bowtie nanoantennas, on the other hand, can be used to focus far-field propagating light down to a nanoscale volume in the optical near-field. The strong and localized field in such a plasmonic "hot-spot" results in strong gradient forces that can be harnessed for trapping of nano-sized objects.
We have fabricated and characterized large-scale arrays of plasmonic nanoantennas for optical near-field trapping of nanoparticles. Merely bottom-up nanofabrication methods are employed to control the size and the spacing of billions of gold triangles on one single substrate with nanometer precision. We show that such nanoantenna arrays can be applied for parallel near-field trapping and for releasing nano-objects with a size and refractive index similar to that of a virus. The laser powers used here are orders of magnitude lower compared to a conventional far-field trapping experiment.